DNS stopped working

[Jason Rotunno]

I don't have a whole lot of experience running DNS.  I set it up on my
linux box for my three domains (the DNS for all three domains points to
the same box that's running the DNS).  The first domain's primary
nameserver is my friend's box and the secondary is my linux box.  This
domain has had no problems and is still working fine.  The second domain
currently only has a primary nameserver which is my box.  This has and
still is working fine as well.  The third domain, though which also only
has a primary nameserver, again being my box, no longer seems to work.  It 
seems to have stopped working within the last day.  If I'm logged into
my box and do an nslookup using my nameserver everything works fine.  If
I do an nslookup from other servers, though it comes back with "non
existent host/domain" and of course I'm unable to connect to it using any
method.  I haven't modified the DNS at all since I've set it up last
spring.  And like I said, the other domain which only uses my box for its
DNS works fine and I'm able to get to it from other servers (maybe 
because it's using cached records on other nameservers?)  I can't seem to
figure out what the problem could be.  It's worked fine since the spring
and all of a sudden the DNS for one of the domains no longer works
(unless I'm on my box using my nameserver).

Another problem that I'm having is that after I start the nameserver
(running bind8.x.x) sometimes it works and sometimes it doesn't.  For
instance...I start the name server, try to do an nslookup and sometimes
it works fine while other times I get:

*** Can't find server name for address 127.0.0.1: No response from server
*** Default servers are not available

and have to re-start.  Other times I start the DNS, it works fine, a day
later I'll be on my box and try to use nslookup and I get the same
message.  Like it konks out or something, although it's still running.

Again, everything has worked fine since the spring.  Then, suddenly, I'm
having these problems.

Oh, finally, I'm currently running this box on my network at my job at a
university.  Is it possible that someone who works with the University's
network services saw that some non university domains were pointing to a
university IP/machine and somehow blocked its use?

If anyone has any suggestions or can anyone point me somewhere to solve
this problem I would appreciate it.  Thanks.

Jason